Transcutaneous Modulated Power Link for a Medical Implant

Abstract

A medical implant system such a Direct Acoustic Cochlear Stimulation and method for generating a transcutanous link between an external module and an internal module. A signal is generated in the external module by modulating an input signal using pulse modulation and then further modulating the pulse modulated signal using digital modulation. In the internal module, the received signal is processed using digital demodulation, the digitally demodulated signal being applied to the input of an amplifier to generate a control signal to control an actuator of the implant. A power component may also be extracted from the received signal in the internal module.

1 . A method of processing an audio signal for transmitting transcutaneously to an internal module of an implanted medical device, the method comprising:
 receiving the audio signal;   converting the audio signal into an electrical signal;   modulating the electrical signal using pulse modulation to provide a pulse modulated signal; and   modulating the pulse modulated signal using a digital modulation to provide a transmission signal for transmitting to the internal module.   
     
     
         2 . A method as claimed in  claim 1  wherein the pulse modulation is Pulse Width Modulation (PWM), 
     
     
         3 . A method as claimed in  claim 1  wherein the pulse modulation is Pulse Density Modulation (PDM). 
     
     
         4 . A method as claimed in  claim 1  wherein the digital modulation is Frequency Shift Keying (FSK). 
     
     
         5 . A method as claimed in  claim 1  wherein the digital modulation is Continuous Phase Frequency Shift Keying (CPFSK). 
     
     
         6 . A method as claimed in  claim 1  wherein the digital modulation is Phase Shift Keying (PSK). 
     
     
         7 . A method as claimed in  claim 1  wherein the digital modulation is On Off Keying (OOK). 
     
     
         8 . (canceled) 
     
     
         8 . A method as claimed in  claim 1  wherein there is provided a frequency ratio between frequencies used in the pulse width modulation and the digital modulation. 
     
     
         9 . A method as claimed in  claim 8  wherein the frequency ratio is an integer. 
     
     
         10 . A method of providing a control signal to an actuator of an implanted hearing device, the method comprising:
 receiving a transmission signal comprising a pulse modulated electrical signal further modulated using digital modulation;   digitally demodulating the received transmission signal to remove the digital modulation; and   applying the demodulated signal to an input of an amplifier to provide the control signal for the actuator.   
     
     
         11 . A method as claimed in  claim 10  wherein the digital demodulation is FSK demodulation. 
     
     
         12 . A method as claimed in  claim 11  wherein the amplifier is a Class D amplifier. 
     
     
         13 . A method as claimed in  claim 12  further comprising extracting a power component from the received transmission signal. 
     
     
         14 . An external module of a hearing implant system for processing an external signal for transmitting transcutaneously to an implanted internal module of the hearing implant system, the external module comprising:
 an input for receiving the external signal and for converting the received external signal into an electrical signal;   a pulse modulator for modulating the electrical signal to provide a pulse modulated signal;   a digital modulator for modulating the pulse modulated signal to provide a transmission signal; and   an antenna for transmitting the transmission signal.   
     
     
         15 . An external module as claimed in  claim 14  wherein the pulse modulator is a Pulse Width Modulation (PWM) modulator. 
     
     
         16 . An external module as claimed in  claim 14  wherein the pulse modulator is a Pulse Density Modulation (PDM) modulator. 
     
     
         17 . An external module as claimed in  claim 14  wherein the digital modulator is a Frequency Shift Keying (FSK) modulator. 
     
     
         18 . An external module as claimed in  claim 14  wherein the digital modulator is a Continuous Phase Frequency Shift Keying (CPFSK) modulator. 
     
     
         19 . An external module as claimed in  claim 14  wherein the digital modulator is a Phase Shift Keying (PSK) modulator. 
     
     
         20 . An external module as claimed in  claim 14  wherein the digital modulator is an On Off Keying (OOK) modulator. 
     
     
         21 . An external module as claimed in  claim 14  wherein the external signal is an acoustic signal and the input is an acoustic transducer. 
     
     
         22 . An external module as claimed in  claim 14  wherein the pulse modulator and the digital modulator are related to each other by a fixed frequency ratio. 
     
     
         23 . An external module as claimed in  claim 22  wherein the fixed frequency ratio is an integer. 
     
     
         24 . An internal module of a hearing implant system comprising:
 a receiver for receiving a transmission signal comprising a pulse modulated electrical signal further modulated using digital modulation;   a digital demodulator for digitally demodulating the received transmission signal; and   an amplifier for receiving the digitally demodulated signal and for providing a control signal to an actuator.   
     
     
         25 . An internal module as claimed in  claim 24  wherein the digital demodulator is an FSK demodulator. 
     
     
         26 . An internal module as claimed in  claim 24  wherein the amplifier is a Class D amplifier. 
     
     
         27 . An internal module as claimed in  claim 24  further comprising the actuator. 
     
     
         28 . An internal module as claimed in  claim 24  further comprising a power extracting circuit for extracting a power component from the received transmission signal. 
     
     
         29 . A Direct Acoustic Cochlear Stimulator system comprising:
 an external module comprising:
 an input for receiving an external signal and for converting the received external signal into an electrical signal; 
 a pulse modulator for modulating the electrical signal to provide a pulse modulated signal; 
 a digital modulator for modulating the pulse modulated signal to provide a transmission signal; and 
 an antenna for transmitting the transmission signal; and 
 an internal module comprising: 
 a receiver for receiving the transmission signal; 
 a digital demodulator for digitally demodulating the received transmission signal; and 
 an amplifier for receiving the digitally demodulated signal and for providing a control signal to an actuator. 
   
     
     
         30 . A Direct Acoustic Cochlear Stimulator system as claimed in  claim 29  wherein the digital demodulator is an FSK demodulator. 
     
     
         31 . A Direct Acoustic Cochlear Stimulator system as claimed in  claim 29  wherein the amplifier is a Class D amplifier. 
     
     
         32 . A Direct Acoustic Cochlear Stimulator system as claimed in  claim 29  further comprising the actuator. 
     
     
         33 . A Direct Acoustic Cochlear Stimulator system as claimed in  claim 29  further comprising a power extracting circuit for extracting a power component from the received transmission signal.